Prenatal Exposure to Airborne and Indoor Pollutants and the Risk of Childhood Neurodevelopmental Disorders

A substantial proportion of Autism Spectrum Disorder (ASD) and Attention-Deficit/Hyperactivity Disorder (ADHD) cases remain without clear etiology, with environmental factors increasingly implicated alongside genetic predispositions. This review synthesizes evidence linking prenatal exposure to outdoor air pollutants and indoor environmental contaminants with childhood behavioral and cognitive impairments. We evaluated peer-reviewed studies examining prenatal exposure to major neurotoxicants—including traffic-related air pollution (TRAP), ultrafine particles, polycyclic aromatic hydrocarbons (PAHs), persistent organic pollutants (POPs), heavy metals, pesticides, bisphenol-A, and phthalates—and their associations with ASD, ADHD, depression, and cognitive deficits. Evidence was integrated by pollutant type, emphasizing mechanistic pathways. Across diverse geographical settings, consistent associations emerged between prenatal exposure to TRAP, PAHs, polychlorinated biphenyls (PCBs), pesticides, and mercury with adverse neurodevelopmental outcomes. Mechanistic studies highlight oxidative stress, neuroinflammation, endocrine disruption, and epigenetic modifications of the placenta as central mediators. Notably, risks were observed even at pollutant concentrations below current World Health Organization (WHO) guidelines, underscoring the heightened vulnerability of the developing brain. Prenatal exposure to a spectrum of environmental pollutants is a plausible and preventable contributor to childhood neurodevelopmental disorders. Enhanced public health measures, stricter environmental regulations, and targeted maternal protection strategies are critical to mitigate these risks.